CN111670095B

CN111670095B - Parallel type integrated driving device

Info

Publication number: CN111670095B
Application number: CN201980005904.4A
Authority: CN
Inventors: 卢载虎; 李载溶; 金大济; 权在星; 梁优成; 梁珍晧; 林贤国
Original assignee: Lee Chi Institute Co ltd
Current assignee: Lee Chi Institute Co ltd
Priority date: 2017-11-23
Filing date: 2019-01-08
Publication date: 2023-01-13
Anticipated expiration: 2039-01-08
Also published as: US11130245B2; KR101983563B1; CN111670095A; WO2019102445A1; US20200384656A1

Abstract

The invention provides a parallel type integrated driving device, which comprises: a drive unit including a first motor, a second motor, a third motor, and a fourth motor; a first shaft, a second shaft, and a third shaft inserted into and formed coaxially with each other through a hollow structure, each shaft being rotatable relative to each other in an inserted state, and each shaft being provided with an end portion extending to an outside of the driving unit; a tip portion provided outside the drive unit and having an operating mechanism mounted thereon; a first link portion, a second link portion, and a third link portion that rotate the tip end portions in pitch, yaw, and roll directions; and a universal link portion connecting a fourth rotor as a rotor of the fourth motor to the distal end portion.

Description

Parallel type integrated driving device

Technical Field

The invention relates to a four-freedom parallel type integrated driving device which is used in joints of robots and the like to realize four degrees of freedom.

Background

The rotating devices of mechanical configuration applied to joints of robots and the like can be classified into series type and parallel type according to a design method and analysis thereof, and the performance of the rotating devices can be measured according to each type of characteristics. The tandem type is suitable for a large working space, and the design and the analysis of the tandem type are relatively easy, so that the tandem type is widely applied.

However, since the tandem type structure is degraded in accuracy due to accumulation of joint errors of the driving device and cannot provide a large power at the end of the structure, a device having a parallel type structure has been recently studied to solve the problem. The parallel arrangement has a high rigidity, a low inertia due to the design that the drive can be placed on the base, a high precision and enables the drive to generate a great power at its end, resulting in a good performance of the rotating device. However, the parallel configuration has many unique features that are difficult to control, small working space and difficult to analyze. Therefore, in order to solve this problem and improve performance, a redundant link structure, overdrive, or a series-parallel combination design is added.

This parallel configuration presents certain problems, and one of the structures derived from the rotational movement of interest is the spherical parallel configuration, in which the axes of rotation of all the joints in the spherical parallel configuration coincide with their fixed points and undergo a pure point-to-center rotational movement. However, since the robot cannot recognize a specific joint motion and cannot provide a sense of position and motion due to the table type device based on the distal end of the spherical parallel structure, it is not intuitive for the specific joint motion.

Whereas exoskeleton type structures can be intuitively controlled by the movement of human joints. However, the arrangement of the joint axes of the rotating device is an important design consideration for the rotating device, since design constraints are high and may lead to movement inconsistencies when the joint axes are not identical.

The above-mentioned contents are only intended to help understanding of the background of the present invention and do not mean that the present invention falls within the scope of the related art known to those skilled in the art.

An example of the related art may be referred to korean patent No. 10-16993246B 1.

Disclosure of Invention

Technical problem

The present invention is proposed to solve such problems, and provides a parallel type integrated driving apparatus capable of: the volume of the whole structure is reduced, the interference of the joint is reduced to the maximum extent, the moving part has low inertia, and the joint movement is realized intuitively.

Technical scheme

In order to achieve the object of the present invention, there is provided a parallel type integrated driving apparatus including: a drive unit constituted by a first motor, a second motor, a third motor, and a fourth motor which are successively stacked in a length direction of the drive unit, and each of the motors is provided with a stator fixed to an outer side of the drive unit and rotors respectively located at inner sides thereof, the rotors rotating relative to each other; first, second, and third shafts, wherein each shaft is provided with one end portion connected to first, second, and third rotors, respectively, which are rotors of the first, second, and third motors, respectively, inside each rotor, each shaft is inserted into each other through a hollow structure and forms a coaxial shaft, each shaft is rotatable relative to each other in an inserted state, and each shaft is provided with another end portion extending toward an outside of the driving unit; a tip portion provided outside the drive unit and having an operating mechanism mounted thereon; a first link section, a second link section, and a third link section, each connecting the first shaft, the second shaft, and the third shaft to the tip end section, respectively, and transmitting rotational forces of the first shaft, the second shaft, and the third shaft to the tip end section, thereby rotating the tip end section in pitch, yaw, and roll directions; and a universal link portion connecting a fourth rotor as a rotor of the fourth motor and the tip end portion to each other.

The first motor, the second motor, the third motor, and the fourth motor are stacked such that the rotation axes of the respective rotors coincide.

The stators and rotors of the first motor, the second motor, the third motor, and the fourth motor have the same size.

The first link portion, the second link portion, and the third link portion are each constituted by a plurality of links.

The second shaft is inserted inside the first shaft, and the third shaft is inserted inside the second shaft.

The third motor is located at the rearmost, and the second motor and the first motor are arranged successively in front of the third motor.

The length of the third shaft is the largest, the length of the second shaft is smaller than that of the third shaft, and the length of the first shaft is smaller than that of the second shaft.

The rear end portion of the third shaft is disposed at the rearmost end, the rear end portions of the second shaft and the first shaft are disposed forward of the third shaft, and the rear end portions of the shafts are connected to the rotors of the corresponding motors.

The front end of the third shaft extends closest to the distal end, and in a direction away from the distal end, a front end of the second shaft and a front end of the first shaft are provided.

The rear end portions of the respective links are connected to the front end portions of the respective shafts, respectively, and the front end portions of the respective links are spaced apart from each other along a peripheral edge of the rear end portion of the tip end portion and connected thereto.

The front end portions of the respective links are spaced apart from each other at the same height along the periphery of the tip end portion and are connected to the tip end portion.

Each link is composed of a first link section and a second link section, wherein a rear end portion of the first link section is rotatably coupled to the shaft, a rear end portion of the second link section is rotatably connected to a front end portion of the first link section, and a front end portion of the second link section is rotatably connected to the tip end portion.

The first link section is bent and extended outward in a state where the rear end portion of the first link section is connected to the shaft, and the second link section is bent inward and connected to the tip end portion after being extended sideward in a state where the rear end portion of the second link section is connected to the front end portion of the first link section.

Any one of the first, second and third rotors is fixed, while the remaining rotors rotate so that the tip portion performs a pitching motion.

The first, second and third rotors rotate in the same size and direction to cause the tip to perform a tumbling motion.

The universal link portion is formed to pass through a center thereof by the tip portion, and is constituted by a joint portion relatively rotatably coupled to the tip portion, and a connecting portion having one side connected to and rotating together with the fourth rotor and the other side relatively rotatably connected to the joint portion.

The joint portion is rotatable relative to the tip portion about a longitudinal axis of the tip portion and relative to the connecting portion about an axis perpendicular to the longitudinal axis of the tip portion.

The connecting portion has a ring shape surrounding an outer side of the joint portion, and includes: a ring portion connected to rotate relative to the joint portion about an axis perpendicular to a longitudinal axis of the tip portion; and a transmission portion connecting the ring portion and the fourth rotor to each other to relatively rotate with the ring portion around an axis perpendicular to an axis connecting the joint portion and the ring portion to each other.

The first, second, third and fourth rotors rotate in the same magnitude and direction so that the tip end portion performs a yaw motion.

The first, second and third rotors are fixed such that the tip portion does not rotate and the fourth rotor rotates such that the joint portion rotates relative to the tip portion.

The connecting portion may extend from an outer side of each link portion to the joint portion side and be connected with the joint portion.

Advantageous effects

According to the parallel type integrated driving device of the invention, when the joint with four degrees of freedom is realized, the free movement can be reproduced, and the collision between the devices is avoided.

By realizing three basic degrees of freedom of pitch, yaw and roll, and simultaneously adding roll (rolling), another motion of the manipulator can be simultaneously realized at the joint end.

The size and the weight of the whole joint driving device can be reduced to the maximum extent while four degrees of freedom are realized.

Drawings

FIG. 1 is a cross-sectional view illustrating a parallel type integrated driving apparatus according to an exemplary embodiment of the present invention;

fig. 2 and 3 are perspective views showing the parallel type integrated driving apparatus shown in fig. 1;

fig. 4 to 10 are views illustrating an operation process of the parallel type integrated driving apparatus shown in fig. 1;

fig. 11 to 17 are another views illustrating the parallel type integrated driving apparatus shown in fig. 1.

Detailed Description

Fig. 1 is a sectional view showing a parallel type integrated drive according to an exemplary embodiment of the present invention, fig. 2 and 3 are perspective views showing the parallel type integrated drive shown in fig. 1, fig. 4 to 10 are views showing an operation process of the parallel type integrated drive shown in fig. 1, and fig. 11 to 17 are another views showing the parallel type integrated drive shown in fig. 1.

Fig. 1 is a sectional view showing a parallel type integrated driving apparatus according to an exemplary embodiment of the present invention, wherein the parallel type integrated driving apparatus according to the present invention includes: a driving unit including a first motor 100, a second motor 200, a third motor 300, and a fourth motor 400 stacked in sequence in a length direction of the driving unit, and each provided with a stator fixed to an outer side of the driving unit and rotors respectively located at inner sides thereof, the rotors rotating relative to each other; a first shaft 160, a second shaft 260, and a third shaft 360, each of which is provided with one end portion connected to the first rotor 140, the second rotor 240, and the third rotor 340, respectively, which are rotors of the first motor 100, the second motor 200, and the third motor 300, respectively, inside the respective rotors, which are inserted into each other through a hollow structure and form a coaxial line, which are rotatable with respect to each other in an inserted state, and which have the other end portion extending toward the outside of the driving unit; a tip part 500 disposed outside the driving unit and having an operating mechanism mounted thereon; a first link part 620, a second link part 640, and a third link part 660, each connecting the first shaft 160, the second shaft 260, and the third shaft 360 to the tip end part 500 and transmitting the rotational force of the first shaft 160, the second shaft 260, and the third shaft 360 to the tip end part 500, thereby rotating the tip end part 500 in pitch, yaw, and roll directions; and a universal link part 460 connecting the fourth rotor 440, which is the rotor of the fourth motor 400, and the tip part 500 to each other.

The parallel type integrated driving device comprises a plurality of motors, wherein three motors are responsible for controlling the pitch, yaw and roll directions of the parallel type integrated driving device, and the rest motors are used for realizing independent rolling. Therefore, the parallel type integrated driving device has four degrees of freedom, so that the joints of a human body can be effectively simulated.

In addition, the parallel type integrated driving device has the following advantages: the size is made compact by stacking four motors, and the size is made more compact by overlapping a plurality of links in the drive module.

In particular, the first motor 100, the second motor 200, the third motor 300, and the fourth motor 400 may be stacked such that the rotation axes of the respective rotors coincide. Further, by making the sizes of the respective stators and rotors the same, the first motor 100, the second motor 200, the third motor 300, and the fourth motor 400 can be made compact in size. Further, a single housing H having a cylindrical shape may be shared.

The first motor 100, the second motor 200, the third motor 300, and the fourth motor 400 are sequentially stacked in the length direction, each of which is provided with a stator fixed to the housing H at the outside thereof, and rotors respectively placed at the inside thereof, the rotors rotating relative to each other.

For each rotor, a shaft is connected to and rotates with the rotor. In particular, in a case where the first, second and

third shafts

160, 260 and 360 are inserted into and formed coaxially with each other through a hollow structure and are capable of rotating relative to each other in an inserted state, one

end portions

162, 262 and 362 are connected to the first, second and

third rotors

140, 240 and 340, respectively, inside the respective rotors. Further, the

other end portions

164, 264 and 364 of the shafts extend toward the outside of the drive unit. In other words, by connecting the three shafts in the form of a hollow structure, the diameter of the entire shaft unit becomes very small, and the entire size becomes compact.

Further, the tip end portion 500 rotated by an actual driving force is provided outside the driving unit, and necessary components are mounted to the tip end portion 500 in various ways. The first, second and

third link portions

620, 640 and 660 respectively connect the first, second and

third shafts

160, 260, 360 to the tip end portion 500 and transmit the rotational forces of the first, second and

third shafts

160, 260, 360 to the tip end portion 500 so that the tip end portion 500 rotates in pitch, yaw and roll directions. Finally, a universal link part 460, which connects the fourth rotor 440 of the fourth motor 400 and the terminal part 500 to each other, is provided at the terminal part 500 side for additionally performing separate independent rolling. Therefore, when the parallel type integrated driving apparatus of the present invention is applied to a joint of a robot or the like, the basic pitch, yaw and roll of the joint are realized, while other joints can also be driven by using another independent rolling motion. For example, when the parallel type integrated driving apparatus of the present invention is applied to a shoulder joint of a robot, an intrinsic movement of a shoulder having two degrees of freedom can be realized, and a bending movement of upper and lower muscles of an arm can be performed together by using an additional rolling. In this case, the elbow does not require a separate actuating mechanism, thereby having an advantage of reducing the size and weight of the entire drive unit.

Meanwhile, the first link part 620, the second link part 640, and the third link part 660 may be respectively composed of a plurality of links. In particular, the rear end of each link may be connected to the front end of each corresponding shaft, and the front end of each link may be spaced apart along and connected to the periphery of the rear end of the tip portion 500. Here, the front end portions of the respective links are spaced apart from each other at the same height along the circumference of the tip end portion 500, and may be connected to the tip end portion 500. Therefore, the length of the tip portion 500 can be reduced, and the volume of the tip portion 500 can be reduced as much as possible. Preferably, the front end portions of the respective links may be spaced apart from each other at intervals of 120 degrees at the same height of the tip end portion 500 and connected to the tip end portion 500.

The links, each of which includes a first link section 720 and a second link section 740, will be described in detail below, wherein a rear end portion of the first link section 720 is rotatably coupled to the shaft, a rear end portion of the second link section 740 is rotatably connected to a front end portion of the first link section 720, and a front end portion of the second link section 740 is rotatably connected to the tip end portion 500. Specifically, as shown in fig. 2, in a state where the rear end portion of the first link 720 is connected to the shaft, the first link 720 is bent and extended outward in the oblique direction, and in a state where the rear end portion of the second link 740 is connected to the front end portion of the first link 720, the second link 740 may be bent inward again toward the tip end portion 500 after being extended once to the side and connected to the tip end portion 500. This configuration of the links can prevent interference during various motions of roll, pitch and yaw.

Meanwhile, as for the shaft coupling method, the second shaft 260 may be inserted into the inside of the first shaft 160, and the third shaft 360 may be inserted into the inside of the second shaft 260. In other words, the three shafts are inserted into each other in the form of a hollow structure, thereby forming one large shaft as a whole. Therefore, the third motor 300 may be located at the rearmost side, the second motor 200 may be disposed in front of the third motor 300, and the first motor 100 may be continuously disposed in front of the second motor 200.

In this combination of shafts and motors, the length of the third shaft 360 may be the longest, and the length of the shaft may be shortened one after another in the order of the second shaft 260 and the first shaft 160. Further, the rear end portion of the third shaft 360 may be located at the rearmost end, the rear end portion of the second shaft 260 may be located in front of the third shaft, the rear end portion of the first shaft 160 may be located in front of the second shaft, and the rear end portion of each shaft may be connected to the rotor of the corresponding motor. Additionally, the front end of the third shaft 360 may extend proximate to the tip portion 500; and the front end portion of the second shaft 260 and the front end portion of the first shaft 160 may be arranged at respective positions in turn in a direction away from the tip end portion 500. With this structure, the shafts are inserted into the hollow structure, and at the same time, the motors can be the same in size, and the shafts are connected to each other at different heights at different angles even when connected to the tip end portion 500, thus having the following advantages: when performing movements such as roll, pitch and yaw, the interference between the links is minimized and the edge angle exhibited by the tip portion 500 is ultimately increased.

In performing the movement, any one of the first, second and

third rotors

140, 240 and 340 may be fixed, and the remaining rotors may rotate, so that the tip portion 500 may perform a pitching movement. Fig. 4 to 6 show the pitch motion of the tip part 500. In this case, the first rotor 140 is fixed and does not move, and thus the first link does not move. In this state, when the second and third links are separated from each other by the rotation of the second and

third rotors

240 and 340, the distal end portion 500 is inclined to the right side, as shown in fig. 4 and 5. And when the second link and the third link approach each other, the distal end portion 500 is inclined to the left side as shown in fig. 5 and 6. Thus, any one of the first, second and

third rotors

140, 240, 340 may be stationary while the remaining rotors rotate so that the tip portion 500 may perform a pitching motion.

Meanwhile, as shown in fig. 6 to 9, when the universal link part 460 is not present, the first, second, and

third rotors

140, 240, and 340 rotate in the same magnitude and direction so that the tip end part 500 can perform a yaw motion. However, in the case of the present invention, because of the presence of the universal link portion 460, the universal link portion 460 should also rotate together for the desired yaw motion. In other words, as shown in fig. 12 to 14, the first, second, third and

fourth rotors

140, 240, 340 and 440 are rotated in the same magnitude and direction, and thus the tip end 500 can perform a yaw motion. When the first, second, third and universal links 460 rotate in the same manner, the tip end 500 as a whole performs a yaw motion. Further, when the first rotor 140, the second rotor 240, and the third rotor 340 are simultaneously rotated while the fourth rotor 440 is fixed, the tumbling motion of the tip portion 500 is achieved, as shown in fig. 14 to 16. In other words, in the absence of the universal link portion 460, when the first rotor 140, the second rotor 240, and the third rotor 340 are simultaneously rotated, yaw is achieved as shown in fig. 6 to 9, and in the presence of the universal link portion 460, roll motion is achieved in a state where the universal link portion 460 is fixed as shown in fig. 14 to 16. In addition, in the case where the universal link part 460 is present, the universal link part 460 is also required to rotate together to perform yaw motion.

Meanwhile, the universal link part 460 is formed to pass through the center thereof by the tip part 500, and the universal link part 460 may be provided with a joint part 468 relatively rotatably coupled to the tip part 500, and a connection part 462 having one side connected to the fourth rotor 440 and rotated together with the fourth rotor 440 and the other side connected to the joint part 468 for relative rotation. Further, the joint 468 may be rotatable relative to the tip 500 about a lengthwise axis of the tip 500, and may be rotatable relative to the connection 462 about an axis perpendicular to the lengthwise axis of the tip 500. Further, the connecting portion 462 has a ring shape surrounding the outer side of the joint portion 468, and the connecting portion 462 may be configured to include: a ring portion 466 connected to rotate relative to the joint portion 468 about an axis perpendicular to the lengthwise axis of the tip portion 500; and a transmission portion 464 connecting the ring portion 466 and the fourth rotor 440 to each other and to the ring portion 466 to rotate relative to the ring portion 466 about an axis perpendicular to an axis connecting the joint portion 468 and the ring portion 466 to each other. With this structure, the roll and yaw of the tip end portion 500 are realized, and as shown in fig. 11 and 12, the gimbal link portion 460 is not disturbed during the pitch and functions as a gimbal.

Meanwhile, as shown in fig. 16 and 17, the first, second, and

third rotors

140, 240, and 340 are fixed such that the tip end portion 500 does not rotate and the fourth rotor 440 rotates. Thus, the joint can rotate relative to the tip 500. Further, by this process, separate and independent rolling of the joint portions can be achieved, and the rolling can be achieved simultaneously with the rolling, pitching, and yawing motions of the tip end portion 500. This single rolling motion is generated by another mechanism so that motion with four degrees of freedom can be output in one joint.

By realizing essentially three degrees of freedom of pitch, yaw and roll, and at the same time increasing roll, another motion of the manipulator can be simultaneously realized at the joint end.

The size and weight of the whole joint driving device can be reduced to the maximum extent while four degrees of freedom are realized.

Although the preferred embodiments of the present invention have been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the technical scope and spirit of the invention as disclosed in the accompanying claims.

Description of the drawings:

100: first motor 200: second motor

300: third motor 400: fourth motor

500: terminal part

Claims

1. A parallel integrated drive device comprising:

a drive unit constituted by a first motor, a second motor, a third motor, and a fourth motor which are successively stacked in a length direction of the drive unit, and each of which is provided with a stator fixed to an outer side of the drive unit and rotors respectively located on inner sides thereof, the rotors rotating relative to each other;

first, second, and third shafts, wherein each shaft is provided with one end portion connected to first, second, and third rotors, respectively, which are rotors of the first, second, and third motors, respectively, inside each rotor, the shafts are inserted into each other through a hollow structure and formed coaxially, the shafts are rotatable relative to each other in an inserted state, and the shafts are provided with the other end portion extending toward the outside of the driving unit;

a tip portion provided outside the drive unit and having an operating mechanism mounted thereon;

a first link portion, a second link portion, and a third link portion, each connecting the first shaft, the second shaft, and the third shaft to the tip end portion, respectively, and transmitting rotational forces of the first shaft, the second shaft, and the third shaft to the tip end portion, thereby rotating the tip end portion in pitch, yaw, and roll directions; and

a universal link portion that connects a fourth rotor as a rotor of the fourth motor and the tip end portion to each other.

2. A parallel integrated drive according to claim 1, wherein the first, second, third and fourth electric motors are stacked such that the axes of rotation of the respective rotors coincide.

3. A parallel integrated drive according to claim 1, wherein the respective stators and rotors of the first, second, third and fourth motors are all of the same size.

4. A parallel integrated drive according to claim 1, wherein the first, second and third link portions are each comprised of a plurality of links.

5. A parallel integrated drive according to claim 1, wherein the second shaft is inserted inside the first shaft and the third shaft is inserted inside the second shaft.

6. A parallel integrated drive according to claim 1, wherein the third motor is located rearwardmost and the second motor and the first motor are arranged successively in front of the third motor.

7. A parallel integrated drive according to claim 1, wherein the third shaft has a maximum length, the second shaft has a length less than the third shaft, and the first shaft has a length less than the second shaft.

8. A parallel integrated drive according to claim 7, wherein the rear end portion of the third shaft is disposed at a rearmost end, the rear end portions of the second and first shafts are disposed forward of the third shaft, and the rear end portion of each shaft is connected to the rotor of the corresponding electric motor.

9. A parallel integrated drive according to claim 7, wherein the front end of the third shaft extends closest to the end, and in a direction away from the end, there are provided the front end of the second shaft and the front end of the first shaft.

10. A parallel integrated drive according to claim 9, wherein the rear ends of the links are connected to the front ends of the shafts, respectively, and the front ends of the links are spaced from each other along the periphery of the rear end of the tip portion and connected thereto.

11. A parallel integrated drive according to claim 10, wherein the front ends of the links are spaced apart from each other at the same height along the periphery of the tip end and are connected to the tip end.

12. A parallel integrated drive according to claim 1, wherein each link is comprised of a first link section and a second link section, wherein a rear end of the first link section is rotatably coupled to a shaft, a rear end of the second link section is rotatably connected to a front end of the first link section, and a front end of the second link section is rotatably connected to the tip end.

13. A parallel type integrated driving apparatus according to claim 12, wherein the first link section is bent and extended to an outside in a state that the rear end portion of the first link section is connected to the shaft, and the second link section is bent and connected to the tip end portion to an inside after being extended to a side in a state that the rear end portion of the second link section is connected to the front end portion of the first link section.

14. A parallel integrated drive according to claim 1, wherein any one of the first, second and third rotors is fixed and the remaining rotors rotate such that the tip portion performs a pitch motion.

15. A parallel integrated drive of claim 1, wherein the first, second and third rotors rotate in the same size and direction to cause the tip to perform a rolling motion.

16. A parallel type integrated driving apparatus according to claim 1, wherein the universal link portion is formed to pass through a center thereof by the distal end portion, and is constituted by a joint portion relatively rotatably coupled to the distal end portion, and a connecting portion having one side connected to the fourth rotor and rotating together with the fourth rotor and the other side relatively rotatably connected to the joint portion.

17. A parallel integrated drive according to claim 16, wherein said articulation section rotates relative to said tip section about a lengthwise axis of said tip section and relative to said connecting section about an axis perpendicular to the lengthwise axis of said tip section.

18. The parallel integrated drive of claim 17, wherein the connecting portion has a ring shape surrounding an outer side of the articulating portion and comprises: a ring portion connected to rotate relative to the joint portion about an axis perpendicular to a longitudinal axis of the tip portion; and a transmission portion connecting the ring portion and the fourth rotor to each other to relatively rotate with the ring portion about an axis perpendicular to an axis connecting the joint portion and the ring portion to each other.

19. A parallel integrated drive of claim 16, wherein the first, second, third and fourth rotors rotate in the same magnitude and direction such that the tip end performs a yaw motion.

20. A parallel integrated drive according to claim 16, wherein the first, second and third rotors are fixed such that the tip portion does not rotate and the fourth rotor rotates such that the articulation section rotates relative to the tip portion.

21. A parallel integrated drive according to claim 16, wherein the connecting portion extends from an outer side of each link portion to the joint portion side and is connected with the joint portion.